The present invention relates to a flexible ballistic resistant article which includes a network of high strength fibers in an elastomeric matrix material.
Various constructions are known for ballistic resistant articles such as vests, curtains, mats, raincoats and umbrellas. These articles display varying degrees of resistance to penetration by high speed impact from projectiles such as BB's, bullets, shells, shrapnel, glass fragments and the like. U.S. Pat. Nos. 5,196,252; 5,187,023; 5,185,195; 5,175,000; 5,167,876; 5,124,195; 5,112,667; 5,061,545; 5,006,390; 4,953,234; 4,916,00; 4,883,700; 4,820,568; 4,748,064; 4,737,402; 4,737,401; 4,681,792; 4,650,710; 4,623,574; 4,613,535; 4,584,347; 4,563,392; 4,543,286; 4,501,856; 4,457,985; and 4,403,012 describe ballistic resistant articles which include high strength fibers made from materials such as extended chain ultra-high molecular weight polyethylene. Typically these fibers are coated, embedded or impregnated with a matrix material such as a polymeric composition or resin.
U.S. Pat. Nos. 5,061,545 and 5,093,158 describe a composite layer of a high strength fibrous network and a resin matrix wherein the fibrous network is nonuniformly impregnated with the resin matrix. The composite layer is formed by feeding the fluid resin matrix onto a fibrous network and passing the resin coated fibrous network through a gap between two compression rolls, at least one of which has a patterned surface. The patterned surface causes the still fluid resin matrix to flow into a non-uniform layer corresponding to the patterned surface. After passing through the rolls, the resin coated fibrous network layer is subjected to heat in order to remove the solvent from the resin matrix, thereby forming a consolidated composite layer which can be used as a prepreg to form a composite having more than one fibrous network. The resulting composite layer has a distribution of resin which is in a pattern wherein there are areas of the composite layer which are thick and have a greater resin to fiber ratio and areas of the composite layer which are thinner and have a lower resin to fiber ratio. The main objective of this composite layer is to increase the volume ratio of fiber to resin which in turn increases the ballistic resistance of a composite made from these layers.
U.S. Pat. No. 5,124,195 describes a fibrous web coated with a polymeric composition wherein the coated web is flexed sufficiently over at least a portion of the web surface to form a plurality of permanent creases distributed the web surface and to increase the flexibility of the web.
Although the ballistic resistant articles described in the above documents provide sufficient protection against most threats, a need exists for further improvement in flexibility without adverse consequences to ballistic performance.